It's the year 2003. Various robots have been developed in the world, and have become of great help in human activities. However, they are only machines that respond to commands. Amidst those robots, Atom is the first in the world to be a robot with a heart, created by Professor Ochanomizu.

Due to a scheme concocted by people who oppose robots, the robots' credibility gradually diminishes, and some are even persecuted by humans. It becomes so that some robots desire to build a robot country, so as to be safe, and to oppose human beings.

At the same time, the former minister of science, Nagamiya Tenma, has built robots that oppose humans, and threw a written challenge to Atom. Why does Professor Tenma persistently challenge Atom? As Atom tries to find the reason behind it, he unravels the secret behind his own birth, and a conecction to Professor Tenma.

What is Professor Tenma's aim? What is the secret behind Atom's birth? What will be of the future of robots and humans? Being tossed around by various incidents, Atom keeps charging forward. Atom has only one wish - "to build a world where people and robots can be friends".